BIOL 1510 Chapter 19

Reducing equivalents

Single electron transfers in the form of NADH and FADH2

Location of ETC

inner mitochondrial membrane

Origin of mitochondria and implication on its structure

An endosymbiosis. This is what gives the mitochondria its inner and outer membrane

Where are the protons pumped out to to set up the electrochemical gradient?

Mitochondrial intermembrane space

What is the energy source for ATP synthesis in oxidative phosphorylation?

electrochemical proton gradient

Three types of electron transfers in the ETC

• direct transfer to Fe3+

• transfer as H+ and electrons

• transfer as hydride (H: -)

How is the electrochemical gradient set up?

Through proton pumping by the ETC complexes

Components of ETC

Complex I, II, III, IV

Overall reaction of complex I

NADH + H+ + Q → NAD+ + QH2

Movement of electrons in complex I

NADH dumps electrons on Coenzyme Q to reduce it twice

Diffusional capabilities of coenzyme Q

Can diffuse across phospholipid bilayer

What is used for electron transfer in complex I?

iron-sulfur complex

Complex II important component

Succinate dehydrogenase

Implication of succinate dehydrogenase as part of complex II

TCA cycle feeds directly into electron transport

Complex III overall reaction

QH2 + 2cyt-C1 (oxidized) + 2H+ → Q + 2cyt-C2 (reduced)

Spectroscopic property of cytochrome C

absorbs visible light

Coenzyme of cytochrome C

heme group

Importance of cytochrome c

mobile electron carrier

Overall reaction of Complex IV

4cyt-C (reduced) + O2→4cyt-C (oxidized) + 2 H2O

Where does pumping of protons occur in ETC?

I, III, IV

Two ways to enter ETC

Complex I→NADH

Complex II→FADH2

What will substrates upstream of an ETC block be?

reduced

What will substrates downstream of an ETC block be?

oxidized

Permeability of inner mitochondrial membrane

Must be impermeable to protons only pass through ATP synthase

How does messing with pH and ion gradient affect ATP synthesis?

Stops ATP synthesis because messes with the electrochemical gradient

Subunits of ATP synthase

F1—sticks into matrix

F0—in membrane